Orienting instructions acquaint subjects with the experimental task and apparatus. Although orienting instructions are a common feature of operant research, their behavioral effects have not been extensively investigated. In the present study, each of four groups received a different set of orienting instructions prior to responding on a multiple fixed-interval, fixed-ratio schedule of reinforcement. Subjects who received the most detailed instructions, which specified the task and the response manipulandum, and in which subjects were advised to earn as many points as possible, showed the least amount of response variability, but they also showed the least sensitivity to programmed contingencies. Subjects that received the same instructions, minus the advice to maximize points, showed less between-subject variability than did the remaining two groups, and greater discrimination between schedule components than did all other groups. Subjects who received instructions that did not specify the task or response manipulandum showed considerable variability in responding and less sensitivity to programmed contingencies. Although orienting instructions may be required for subjects to contact the experimental contingencies, some orienting instructions influence subjects' sensitivity to the experimental contingencies more than others.In the experimental analysis of human behavior, instructions are typically used for two reasons: to orient subjects to the apparatus and task (i.e., orienting instructions), and to specify experimental contingencies (i.e., contingency-specifying instructions). Although effects of the latter on behavior have been investigated in some detail (for a review, see Baron & Galizio, 1983), the effects of the former have been examined only rarely (e.g., see Terrell, Bennett, Buskist, & Williams, 1986). Furthermore, although the effects of contingency-specifying instructions have been addressed, the effects of such instructions have typically not been separated from possible effects of orienting instructions per se, thus providing a possible methodological confound.In one study of the effects of orienting instructions (Terrell et al., 1986), four groups of subjects received different orienting instructions prior to being exposed to a fixedinterval (FI) schedule of reinforcement. Orienting instructions differentially affected response rates of subjects across each of the groups. Subjects in the group that was told to "earn as many points as possible" (maximum instructions) responded at the highest rates, and the group that received minimal instructions (no mention of the experimental task or apparatus) responded at the lowest rates. Terrell et al. concluded that orienting instructions may interact with contingency-specifying instructions to control human performance in operant contexts. Unfortunately, Terrell et al. did not examine the effects of orientin~ instructions on subjects' sensitivities to schedRequests for reprints may be addressed to Richard J. DeGrandpre or William Buskist, Psychology Depar...